Subject: Re: [PATCH v4] rev-list: refuse --first-parent combined with --bisect

From: Junio C Hamano <[email-masked]>
Date: Tue, 10 Mar 2015 15:09:54 -0700

Kevin Daudt <[email-masked]> writes:

> rev-list --bisect is used by git bisect, but never together with
> --first-parent. Because rev-list --bisect together with --first-parent
> is not handled currently, and even leads to segfaults, refuse to use
> both options together.
>
> Suggested-by: Junio C. Hamano <[email-masked]>
> Helped-by: Eric Sunshine <[email-masked]>
> Signed-off-by: Kevin Daudt <[email-masked]>
> ---
> Changes since v3:
>
> * Added an ifdef::git-rev-list[] guard around the warning in the
>   --first-parent section so that it only shows up in `man git-rev-list`
>   and not in `man git log`
>
> * Added the warning also to the --bisect section.

I wonder what "git log --first-parent --bisect A..B" should do,
though.

Wouldn't the rejection belong to revision.c::setup_revisions(),
where we reject combined use of (--reverse, --walk-reflogs) and
(--children, --parents), to apply this to all commands in the "log"
family that uses the revision walker machinery?

>
>  Documentation/rev-list-options.txt | 4 ++++
>  builtin/rev-list.c                 | 3 +++
>  t/t6000-rev-list-misc.sh           | 4 ++++
>  3 files changed, 11 insertions(+)
>
> diff --git a/Documentation/rev-list-options.txt b/Documentation/rev-list-options.txt
> index 4ed8587..a148672 100644
> --- a/Documentation/rev-list-options.txt
> +++ b/Documentation/rev-list-options.txt
> @@ -124,6 +124,9 @@ parents) and `--max-parents=-1` (negative numbers denote no upper limit).
>  	adjusting to updated upstream from time to time, and
>  	this option allows you to ignore the individual commits
>  	brought in to your history by such a merge.
> +ifdef::git-rev-list[]
> +	Cannot be combined with --bisect.
> +endif::git-rev-list[]
>  
>  --not::
>  	Reverses the meaning of the '{caret}' prefix (or lack thereof)
> @@ -567,6 +570,7 @@ would be of roughly the same length.  Finding the change which
>  introduces a regression is thus reduced to a binary search: repeatedly
>  generate and test new 'midpoint's until the commit chain is of length
>  one.
> +Cannot be combined with --first-parent.
>  
>  --bisect-vars::
>  	This calculates the same as `--bisect`, except that refs in
> diff --git a/builtin/rev-list.c b/builtin/rev-list.c
> index ff84a82..f5da2a4 100644
> --- a/builtin/rev-list.c
> +++ b/builtin/rev-list.c
> @@ -291,6 +291,9 @@ int cmd_rev_list(int argc, const char **argv, const char *prefix)
>  	if (revs.bisect)
>  		bisect_list = 1;
>  
> +	if (revs.first_parent_only && revs.bisect)
> +		die(_("--first-parent is incompattible with --bisect"));
> +
>  	if (DIFF_OPT_TST(&revs.diffopt, QUICK))
>  		info.flags |= REV_LIST_QUIET;
>  	for (i = 1 ; i < argc; i++) {
> diff --git a/t/t6000-rev-list-misc.sh b/t/t6000-rev-list-misc.sh
> index 2602086..1f58b46 100755
> --- a/t/t6000-rev-list-misc.sh
> +++ b/t/t6000-rev-list-misc.sh
> @@ -96,4 +96,8 @@ test_expect_success 'rev-list can show index objects' '
>  	test_cmp expect actual
>  '
>  
> +test_expect_success '--bisect and --first-parent can not be combined' '
> +	test_must_fail git rev-list --bisect --first-parent HEAD
> +'
> +
>  test_done